Method of making commutator structure for the rotor of a dynamo-electric machine

ABSTRACT

A commutator structure for use on the rotor of a dynamo-electric machine includes a cylindric assembly of commutator segments held together by shrink rings. The commutator segment assembly is mounted on a cylindric support part such as a bush or the rotor shaft itself, there being established between the commutator segment assembly and support part an annulus with an elastic layer. Preferably the elastic layer is constituted by absorbant material such as fiber glass impregnated with a thermo-setting synthetic resin.

United States Patent Hell et al.

[4 1 Sept. 30, 1975 METHOD OF MAKING COMMUTATOR STRUCTURE FOR THE ROTOROF A DYNAMO-ELECTRIC MACHINE Inventors: Werner Heil, Birr, Switzerland;

Heinrich Moser, Waldshut,

Germany Assignee: Aktiengesellschaft Brown, Boveri & Cie., Baden,Switzerland Filed: Feb. 26, 1974 Appl. No: 445,956

Related US. Application Data Division of Ser. Nov 259,572, June 5. 1972,abandoned.

Foreign Application Priority Data June 15. 1971 Switzerland 8683/71 US.Cl. 29/597; 310/42; 310/43; 310/235; 310/236 Int. Cl. HOlR 43/06 Fieldof Search 29/597. 205 CM; 310/233. 310/235, 236, 42. 43, 45

[56] References Cited UNITED STATES PATENTS 1.329.277 l/1920 Van Dusen29/597 X 2.501.502 3/1950 Fletcher 310/236 2.606.220 8/1952 Labastie310/236 3,290,527 12/1966 Habermann 29/597 X 3.643.314 2/1972 Worner etal. 29/205 CM Primary Eraminer-Carl E. Hall Attorney, Agent, orFirmPierce, Scheffler & Parker 5 7 ABSTRACT A commutator structure foruse on the rotor of a dynamo-electric machine includes a cylindric assembly of commutator segments held together by shrink rings. The commutatorsegment assembly is mounted on a cylindric support part such as a bushor the rotor shaft itself, there being established between thecommutator segment assembly and support part an annulus with an elasticlayer. Preferably the elastic layer is constituted by absorbant materialsuch as fiber glass impregnated with a thermo-setting synthetic resin.

6 Claims, 3 Drawing Figures US. Patent Spt. 30,1975 3,908,265

Fz PRIOR ART METHOD OF MAKING COMMUTATOR STRUCTURE FOR THE ROTOR OF ADYNAMO-ELECTRIC MACHINE This is a division of application Ser. No.259,572 filed June 5, 1972 now abandoned.

The present invention relates to a commutator component for the rotor ofa dynamo-electric machine which is of improved construction, and also toan improved method for securing the commutator to the part on which itis supported.

It is already known to secure a cylindric assembly of commutatorsegments onto the supporting part which latter may be an insulatedmetallic bush or an insulated part of the rotor shaft itself by means ofshrink rings which engage the cylindric assembly. The shrink ringsperform not only the function of holding the commutator segmentstogether but also serve to establish an arch pressure intended toprevent individual commutator segments from moving radially outwardwhile the rotor is in operation as a result of the centrifugal forcesacting upon them. However, the known arrangements of this type have notbeen found satisfactory for use on rotors operating at high speeds.Moreover, in an embodiment utilizing an insulated bush, the latter mustbe precision-machined which adds to the overall costs of production.

The principal objective of this invention is to provide an improvedstructure which does not suffer from these disadvantages and in whichthe individual commutator segments are prevented from shifting radiallyoutward regardless of the speed at which the commutatorequipped rotoroperates.

The improved mode of connection between the cylindric commutator segmentassembly and the part on which it is supported, bush or shaft, isprincipally characterized by the use of an elastic layer intermediatethe commutator segment assembly and support part, the elastic layerpreferably being a plastic, more specifically a thermosetting syntheticresin which is heat hardened following introduction into an annulus ofabsorbant material between the commutator segment assembly and thesupport part and which is impregnated by the resin. The absorbantmaterial is preferably glass fiber either in the form of a fabric or mator helically wound-on glass fiber cord.

An advantageous method of producing the improved commutator structure ascombined with its support part is to first secure the commutatorsegments of the cylindric assembly together by means of the shrinkrings, then bring the cylindric assembly into position on the bush orshaft, as the case may be, and then fill the annulus between the twowith the elastic material, which secures the commutator segment assemblyto the supporting part. The elastic material may be applied directlyinto the annulus, or the annulus may be first provided with a filling ofan absorbant material, e.g. fiber glass which is then impregnated withthermosetting synthetic resin and thereafter heat-hardened. Preferably,the absorbant material to receive the thermo-setting resin is applied tothe supporting part for the cylindric commutator segment assembly beforethe latter is placed into position on the supporting part.

The foregoing as well as other objects and advantages of the inventionwill become more apparent from the following detailed description of twoembodiments thereof and the accompanying drawings wherein:

FIG. I is a longitudinal section through a part of a conventionallymounted cylindric commutator segment assembly; 1

FIG. 2 is also a longitudinal section illustrating one mode of mountingthe commutator segment assembly on its cylindrical support in accordancewith the invention; and I FIG. 3 is a view similar to FIG. 2illustrating another mode of mounting thecommutator segment assembly onits cylindrical support according to the invention.

With reference now to the drawings and to FIG. I in particular, theconventional commutator structure there depicted, and as to which thepresent invention constitutes a marked improvement, includes a metallicbush2 having thereon a sleeve 3 of insulating material on which thecylindric assembly of commutator segments 1 is secured by means ofaxially spaced shrink rings 6 and 7.- As previously indicated, thearchpressure created by the shrink rings is designedto preventindividual segments 1 from shifting radially outward while the rotor ofthe dynamo-electric machine on which the bush 2' is mounted is rotating.However, the radially inward force Fl created by the shrink'rings 6,7 ispartially reduced by a counter-acting centrifugal force F2 acting uponeach of the commutator segments. As a consequence, the mode of mountingthe commutator segment assembly depicted in FIG. 1 is not suitable foroperation of the' rotor at high speeds. Moreover, the insulated bush 2must be precision-machined.

These disadvantages are overcome by use of the improved constructionaccording to the invention asdepicted in FIGS. 2 and 3, respectively. InFIG. 2, the bush 2 is provided with an insulating sleeve 3 whichincludes a glass fiber fabric and/or mica, and located between sleeve 3and the inner circumference of the cylindric assembly of commutatorsegments 1 is an elastic layer 4 having a'thickne ss of from 1 to 3 mm.and preferably between 1.5 and 2.0 mm. The intermediate layer 4 consistsessentially of absorbent glass fiber mat or, as illustrated, anabsorbant glass fiber cord 5 which is wound helically on the insulatingsleeve 3 with the adjacent turns close to each other, the glass fibermat or cord, as the case may be, being impregnated with an elasticmaterial, preferably any of the well known thermosetting syntheticresins.

The preferred mode of procedure to produce the improved commutatorstructure depicted in FIG. 2 is to first mount the cylindric assembly ofcommutator segments, held together by the axially spaced shrink rings 6,7 with an intermediate insulating ring being provided to electricallyisolate the rings from the commutator segments, on the assembly of bush2, absorbant insulating sleeve 3 and absorbant layer 5. The annulus thusformed by the absorbant insulating sleeve 3 and absorbant layer 5between the outer surface of bush 2 and inner surface of the commutatorsegment assembly 1 is then completely impregnated with the thermosettingsynthetic resin and heat-hardened. The synthetic resin impregnatedannulus between bush 2 and commutator segment assembly 1 forms asufficiently elastic intermediate layer and also cements the layer tothe bush 2 and commutator segment assembly 1. Moreover, since theconnecting surface areas between the intermediate layer and the bush andcommutator segment assembly, respectively are relatively large, theshearing stress appearing at the connecting surfaces is relatively low.

FlG. 3 illustrates a slightly different embodiment wherein the cylindricassembly of commutator segments 1 is mounted directly on the rotor shaft2' itself rather than on a separate bush as in FIG. 2. The shrink rings6 and 7' do not engage the exterior surface of the commutator segmentassembly 1 as in FIG. 2 but rather are seated in annular recesses formedat the opposite ends of the assembly and properly electrically insulatedfrom the assembly. The surface of shaft 2 carries the insulating sleeve3', and the cylindric commutator segment assembly 1, which may have aninner diameter of about 200 mm, for example, is centered about thesleeve 3 with an annular gap of about 2 mm, for example, between thesleeve and segment assembly, which is thereafter filled with athermosetting synthetic resin which is then heat hardened to establishthe desired intermediate elastic layer 4.

The provision of the elastic layer 4 or 4 intermediate the commutatorsegment assembly and mounting part, bush 2 or shaft 2 eliminates anypossible net reduction in the arch pressure produced by the shrinkrings. With practically the same expenditure of working material, onethus obtains a better technical product and at a lower production costthan has heretofore been possible.

We claim:

l. The method of producing and mounting a commutator structure for adynamo-electric machine on a cylindric support part thereof whichcomprises the steps of:

assembling the commutator segments in a cylindric array,

applying shrink rings to said cylindric array of commutator segments tosecure them together and establish a predetermined arch pressurethereon,

bringing said cylindric array of commutator segments into position oversaid cylindric support part, the

inner diameter of said cylindric array of commuta- I tor segments beinggreater than the outer diameter of said support part thereby toestablish an annulus therebetween,

filling said annulus with an elastic insulating material comprisingglass fibers impregnated with a thermoset synthetic resin, and

cementing said elastic insulating material to the inner periphery ofsaid shrink ring secured commutator segment array and to the peripheryof said cylindric support part, the elasticity of said insulatingmaterial which fills said annulus serving to prevent any possiblereduction in the arch pressure produced by said shrink rings.

2. The method as defined in claim 1 of producing and mounting acommutator structure for a dynamoelectric machine wherein said cylindricsupport part includes a metallic bush having a sleeve of electricalinsulating material thereon which is cemented to said elastic insulatingmaterial.

3. The method as defined in claim 2 of producing and mounting acommutator structure for a dynamoelectric machine on a cylindricalsupport part thereof wherein said sleeve of insulating material includesa glass fiber fabric.

4. The method as defined in claim 2 of producing and mounting acommutator structure for a dynamoelectric machine on a cylindricalsupport part thereof wherein said sleeve of insulating material includesmica.

5. The method as defined in claim 1 of producing and mounting acommutator structure for a dynamoelectric machine wherein the glassfiber in said elastic insulating material is formed as a mat.

6. The method as defined in claim 1 of producing and mounting acommutator structure for a dynamoelectric machine wherein the glassfiber in said elastic insulating material is formed as a closely woundhelical coil.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3308,265 DATED Sept- 3 975 INVENTOR(S) Werner Heil, et a1 it is certifiedthat error appears in the ab0ve-identified patent and that said LettersPatent are hereby corrected as shown below:

[73] Assignee: BBC AKIIENGESEILSCHAFT BROWN,BOVERI 8c CIE.

Signed and Scaled this thirtieth Day of mm 1975 [SEAL] AUCSL' RUTH C.MASON C. IAISIIALL DAN" Arresting Officer Commissioner a] hull: andTrademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENTNO. 3 ,9 8,26 DATED p 3 975 INVENTOR(S) Werner Heil, et a1 It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown betow:

[73] Aissignee: BBC AKTIENGESEILSCHAFT BRCWILBOVERI thirtieth Day ofDecember 1975 [SEAL] A ttes t:

RUTH C. MASON Arresting Officer C. IAISIIAl-l. DANN Commissioner of luauand Trademarks

1. The method of producing and mounting a commutator structure for adynamo-electric machine on a cylindric support part thereof whichcomprises the steps of: assembling the commutator segments in acylindric array, applying shrink rings to said cylindric array ofcommutator segments to secure them together and establish apredetermined arch pressure thereon, bringing said cylindric array ofcommutator segments into position over said cylindric support part, theinner diameter of said cylindric array of commutator segments beinggreater than the outer diameter of said support part thereby toestablish an annulus therebetween, filling said annulus with an elasticinsulating material comprising glass fibers impregnated with athermo-set synthetic resin, and cementing said elastic insulatingmaterial to the inner periphery of said shrink ring secured commutatorsegment array and to the periphery of said cylindric support part, theelasticity of said insulating material which fills said annulus servingto prevent any possible reduction in the arch pressure produced by saidshrink rings.
 2. The method as defined in claim 1 of producing andmounting a commutator structure for a dynamo-electric machine whereinsaid cylindric support part includes a metallic bush having a sleeve ofelectrical insulating material thereon which is cemented to said elasticinsulating material.
 3. The method as defined in claim 2 of producingand mounting a commutator structure for a dynamo-electric machine on acylindrical support part thereof wherein said sleeve of insulatingmaterial includes a glass fiber fabric.
 4. The method as defined inclaim 2 of producing and mounting a commutator structure for adynamo-electric machine on a cylindrical support part thereof whereinsaid sleeve of insulating material includes mica.
 5. The method asdefined in claim 1 of producing and mounting a commutator structure fora dynamo-electric machine wherein the glass fiber in said elasticinsulating material is formed as a mat.
 6. The method as defined inclaim 1 of producing and mounting a commutator structure for adynamo-electric machine wherein the glass fiber in said elasticinsulating material is formed as a closely wound helical coil.